Question

Find the volume of the solid obtained by revolving the region bounded by y=x^2, y=0, x=0, and x=9 about the y-axis.

Can someone explain how to solve this?

Answer 1

well the formula is

\[V = \pi \int\limits_{f(a)}^{?f(b)} (x^2) dy\]

and the graph looks like



so you know x^2 and the question becomes

\[V = \pi \int\limits\limits_{0}^{?81} (y) dy\]